1. Field of the Invention
The present invention is related to a method for enhancing the secretion of GLP-1 of the intestinal endocrine cell using bitter compound.
2. The Prior Arts
Glucagon-like peptide, GLP-1, a member of glucagon peptide family having 30 or 31 amino acids, is a known type of incretin which is secreted from intestinal endocrine L-cells. As a nerve reflex mechanism, GLP-1 is secreted within minutes after the food intake as well as when the food directly contact the intestinal endocrine L-cells. The functions of GLP-1 are as follow: enhancing the secretion of glucose-dependent insulin of pancreatic beta cells, increasing insulin sensitivity, suppressing the secretion of glucagon, suppressing appetite, lowering gastric emptying rate, and enhancing the growth, differentiation and regeneration of pancreatic beta cells as well as preventing them from apoptosis. When L-cells are stimulated, membrane depolarization and the increase of intracellular cAMP or Ca2+ concentration promotes intracellular secretary vesicles to fuse with cellular membrane, thus, resulting in the release of GLP-1. However, once GLP-1 is secreted from L-cells, it is soon degraded by dipeptidyl peptidase 4, DPP-4, which is extensively distributed in blood plasma, epidermal cells or the surface of endothelial cells. Only 10-15% of the secreted GLP-1 can enter the systemic circulation in its active form and its half-life in the systemic circulation is approximately 2 minutes.
Triterpenoids are metabolites of isopentenyl pyrophosphateoligomers consist of 30 carbon atoms and are mostly formed by the linkage of 6 isoprene units. According to estimation, there are more than 2,000 types of triperpenoid naturally existed in animals or plants. Triperpenoid in plants are mostly in the form of free, glycosides, or ester, and are mainly tetracyclic or pentacyclic triperpenoid compounds. There are many known pharmaceutical and pharmacological effects of triperpenoid compounds, such as: anti-inflammation, analgesia, cardiotonic, sedative, anti-oxidation, anti-virus, anti-bacterial, anti-allergic, antipruritic, antiangiogensis and muscle relaxation.
As mentioned above, the physiological phenomenon of intestinal endocrine L-cells detecting certain food or nutrients and resulting in the secretion of insulin to decrease blood glucose level via hormone stimulation is called incretin effect. Intestinal endocrine L-cell is located in intestine tract and the different taste receptors on its membrane are directly exposed to nutrients or substances in the intestine tract enhancing the secretion of metabolic hormone.
In light of the ability of adjusting blood glucose level and the limitation of reaction time and activity of incretin, as well as the feasibility of stimulating taste receptors on the intestinal endocrine L-cells located in the intestine tract to cause incretin effect as described above, it is necessary to provide a medicament or healthy victual which is able to regulate the secretion of GLP-1 of the intestinal endocrine L-cells upon discovering specific receptor-ligand interactions.